Nowadays, dripping injection medical technique is widely utilized in every hospital. Dripping injection to be done frequently requires several hours. In addition, there are large numbers of sick cases need dripping injection care. Therefore, after the dripping injection device has been connected to a patient, the medical personnel leave this patient alone and go out to see another patient, and only occasionally come to watch the status of their patients. As to patients, they frequently have psychological burden and feel uneasy or afraid that air may to into their blood vessel when dripping injection fluid is completely used up without medical personnel to take care of it. Therefore, they can't sleep, even feel very tired. They still open their eyes to watch the status of injection fluid.